From 00b7385e4c1b8ab341f827323eeca77109349ef0 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Fri, 4 Mar 2016 16:44:30 -0500
Subject: correctly restore VCA-VCA slave/master relationships at session load
 time

---
 libs/ardour/ardour/gain_control.h |  4 +++-
 libs/ardour/ardour/vca_manager.h  |  4 ++++
 libs/ardour/gain_control.cc       | 39 +++++++++++++++++++++++++++++----------
 libs/ardour/vca_manager.cc        |  6 ++++++
 4 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/libs/ardour/ardour/gain_control.h b/libs/ardour/ardour/gain_control.h
index c44a76dd04..2b472dc8e0 100644
--- a/libs/ardour/ardour/gain_control.h
+++ b/libs/ardour/ardour/gain_control.h
@@ -91,12 +91,14 @@ class LIBARDOUR_API GainControl : public AutomationControl {
 	typedef std::map<uint32_t,MasterRecord> Masters;
 	Masters _masters;
 	PBD::ScopedConnectionList masters_connections;
-	std::string _masters_state_string ();
+	std::string masters_string;
+	PBD::ScopedConnection vca_loaded_connection;
 
 	gain_t get_value_locked () const;
 	gain_t get_master_gain_locked () const;
 	void master_going_away (boost::weak_ptr<VCA>);
 	void recompute_masters_ratios (double val);
+	void vcas_loaded();
 
 	void _set_value (double val, PBD::Controllable::GroupControlDisposition group_override);
 };
diff --git a/libs/ardour/ardour/vca_manager.h b/libs/ardour/ardour/vca_manager.h
index 4e5b54f438..c51336b558 100644
--- a/libs/ardour/ardour/vca_manager.h
+++ b/libs/ardour/ardour/vca_manager.h
@@ -50,17 +50,21 @@ class VCAManager : public SessionHandleRef, public PBD::StatefulDestructible
 
 	VCAList vcas() const;
 
+	PBD::Signal0<void>          VCAsLoaded;
 	PBD::Signal1<void,VCAList&> VCAAdded;
 	PBD::Signal1<void,VCAList&> VCARemoved;
 
 	XMLNode& get_state();
 	int set_state (XMLNode const&, int version);
 
+	bool vcas_loaded() const { return _vcas_loaded; }
+
 	static std::string xml_node_name;
 
      private:
 	mutable Glib::Threads::Mutex lock;
 	VCAList _vcas;
+	bool _vcas_loaded;
 
 	void clear ();
 };
diff --git a/libs/ardour/gain_control.cc b/libs/ardour/gain_control.cc
index b9c381c406..3eff20b1f1 100644
--- a/libs/ardour/gain_control.cc
+++ b/libs/ardour/gain_control.cc
@@ -348,22 +348,41 @@ GainControl::set_state (XMLNode const& node, int version)
 
 	XMLProperty const* prop = node.property (X_("masters"));
 
-	/* XXX Problem here if we allow VCA's to be slaved to other VCA's .. we
-	 * have to load all VCAs first, then call ::set_state() so that
-	 * vca_by_number() will succeed.
+	/* Problem here if we allow VCA's to be slaved to other VCA's .. we
+	 * have to load all VCAs first, then set up slave/master relationships
+	 * once we have them all.
 	 */
 
 	if (prop) {
-		vector<string> masters;
-		split (prop->value(), masters, ',');
+		masters_string = prop->value ();
 
-		for (vector<string>::const_iterator m = masters.begin(); m != masters.end(); ++m) {
-			boost::shared_ptr<VCA> vca = _session.vca_manager().vca_by_number (PBD::atoi (*m));
-			if (vca) {
-				add_master (vca);
-			}
+		if (_session.vca_manager().vcas_loaded()) {
+			vcas_loaded ();
+		} else {
+			_session.vca_manager().VCAsLoaded.connect_same_thread (vca_loaded_connection, boost::bind (&GainControl::vcas_loaded, this));
 		}
 	}
 
 	return 0;
 }
+
+void
+GainControl::vcas_loaded ()
+{
+	if (masters_string.empty()) {
+		return;
+	}
+
+	vector<string> masters;
+	split (masters_string, masters, ',');
+
+	for (vector<string>::const_iterator m = masters.begin(); m != masters.end(); ++m) {
+		boost::shared_ptr<VCA> vca = _session.vca_manager().vca_by_number (PBD::atoi (*m));
+		if (vca) {
+			add_master (vca);
+		}
+	}
+
+	vca_loaded_connection.disconnect ();
+	masters_string.clear ();
+}
diff --git a/libs/ardour/vca_manager.cc b/libs/ardour/vca_manager.cc
index 9a96dc8a38..71c3fe8029 100644
--- a/libs/ardour/vca_manager.cc
+++ b/libs/ardour/vca_manager.cc
@@ -33,6 +33,7 @@ string VCAManager::xml_node_name (X_("VCAManager"));
 
 VCAManager::VCAManager (Session& s)
 	: SessionHandleRef (s)
+	, _vcas_loaded (false)
 {
 }
 
@@ -140,6 +141,8 @@ VCAManager::set_state (XMLNode const& node, int version)
 	XMLNodeList const & children = node.children();
 	VCAList vcal;
 
+	_vcas_loaded = false;
+
 	for (XMLNodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
 		if ((*i)->name() == VCA::xml_node_name) {
 			boost::shared_ptr<VCA> vca = boost::shared_ptr<VCA> (new VCA (_session, **i, version));
@@ -158,6 +161,9 @@ VCAManager::set_state (XMLNode const& node, int version)
 		}
 	}
 
+	_vcas_loaded = true;
+
+	VCAsLoaded (); /* EMIT SIGNAL */
 	VCAAdded (vcal); /* EMIT SIGNAL */
 
 	return 0;
-- 
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